Making a baby: mom + dad + mom

In February 2015, the British Parliament approved the creation of a human embryo from the DNA of three people: mother, father and a donor mother. The modified in-vitro fertilization (IVF) technique, called mitochondrial replacement therapy (MRT), would help some mothers with known rare mitochondrial mutations avoid passing on unhealthy defects. These defects can cause severe or deadly diseases, which are often incurable, such as muscular dystrophy, heart and kidney disease, liver failure and severe muscle weakness. Approximately 99.9 percent of our DNA comes from our mother and father. The donor mother would provide the additional 0.1 percent of DNA, specifically the healthy mitochondrial DNA, for the embryo before or after fertilization.

Mitochondria, also called the “powerhouse of the cell,” convert food into usable energy. They are passed down only by the mother and have their own DNA, but they do not affect a person’s character traits or personal appearance. All of our physical features and personalities come from nuclear DNA passed down from our parents.

Skeptics of MRT are concerned about safety and ethical considerations. Is even minimal genetic engineering a slippery slope that borders on scientists and parents “playing God”? Are we inching toward human eugenics or “designer babies” programs? In a Wall Street Journal opinion piece, bioethicist and psychiatrist Robert Klitzman wrote, “I would argue that it’s not, that this is equivalent to changing the batteries in some fancy machine. The machine is the same. Sort of like getting a blood transfusion or an organ transplant, it doesn’t change the identity of the person.” However, these are valid concerns, especially if governments do not monitor how far someone will go to manipulate the human makeup.

In the 1996 science fiction comedy Multiplicity, Michael Keaton’s character, Doug Kinney, is a family man and construction worker who never has enough time to keep up with his growing list of demands at home and work. With too much to do and not enough time to do it, Doug is given the opportunity to clone himself in order to try to get control of his life’s stresses. When one clone isn’t enough, he then creates a clone-of-a-clone and then another. Each duplicate Doug seems to be less “sharp” than the original. The movie ludicrously makes the point that humans maybe aren’t the best creators of human life.

Scientists are also concerned that there is an unknown long-term impact of changing a person’s genetic makeup. There’s still quite a bit of unknowns in manipulating the human genome. At this point, MRT definitely isn’t for everyone. It would only benefit a small subset of the population (up to 1,000 to 4,000 affected births per year in the United States per the United Mitochondrial Disease Foundation). If there ever is a day where parents could choose their baby’s eye and hair color, intelligence or physical attributes, then there are many more ethical discussions ahead.

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About Dr. Justin Morgan, Bundoo Pediatrician

Justin Morgan, MD, FAAP, is a board-certified pediatrician who practices general pediatrics in Louisville, Kentucky. He cares for children of all ages.


  1. The way you ended this post really gets to the heart of the controversy: it’s not current or intended uses but the potential implications that are dangerous. Kind of like Apple’s battle with the FBI recently: once you do it, it’s there and can’t be undone, leaving the potential to be used in ways unplanned.

  2. I think it can be very easy to start the comparison to science fiction (and that Multiplicity movie is a great one :), but I know most people would use this technology in a heartbeat if they carried a fatal genetic disorder that could be prevented in this way. I know I would! We used to think surrogacy was this “out there”…but luckily we’ve realized there are many wonderful alternative ways to make happy, healthy families!

    1. Good point. Technological advancement is usually feared before it is embraced.


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